Thermal control system

Abstract

A thermal control unit for delivering temperature-controlled fluid to one or more patient therapy devices (e.g. pads, blankets, etc.) that are in contact with a patient is disclosed. The thermal control unit includes a fluid circuit with an inlet and outlet, a reservoir, a heat exchanger, a pump, and a controller. The thermal control also includes any one or more of the following: (1) an air eliminator with an air filter for filtering air vented from the fluid circuit to the ambient surroundings; (2) a plug that moves in response to changing fluid levels and that fluidly isolates the air filter from the fluid; (3) a second air filter coupled to the reservoir; (4) a check valve to prevent fluid from back flowing into the reservoir; and/or (5) a liquid filter coupleable to the reservoir to filter liquid entering or exiting the reservoir.

What is claimed is: 
     
       1. A thermal control unit comprising:
 a fluid circuit having a fluid outlet adapted to couple to a fluid supply line and a fluid inlet adapted to couple to a fluid return line; 
 a reservoir for supplying a liquid to the fluid circuit, the reservoir positioned outside of the fluid circuit such that fluid returning from the fluid return line is pumped back to the fluid supply line without passing through the reservoir; 
 a heat exchanger in the fluid circuit and adapted to change a temperature of the liquid in the fluid circuit; 
 a pump for circulating the liquid supplied by the reservoir through the fluid circuit; 
 a liquid filter coupleable to the reservoir, the liquid filter positioned such that filling the reservoir with the liquid requires passing the liquid through the liquid filter when the liquid filter is coupled to the reservoir; 
 an air eliminator for venting air from the fluid circuit to the ambient surroundings; 
 a first air filter coupled to the air eliminator, the first air filter adapted to filter particulates from the air vented to the ambient surroundings; 
 a second air filter coupled to the reservoir, the reservoir being fluidly sealed from the ambient surroundings except at a location of the second air filter, the second air filter adapted to filter particulates from air vented out of the reservoir to the ambient surroundings; and 
 a controller adapted to control the heat exchanger such that a temperature of the circulating liquid is adjustable toward a desired temperature. 
 
     
     
       2. The thermal control unit of  claim 1 , wherein the air eliminator includes a plug having a position that varies in response to a level of the liquid in the thermal control unit, the plug adapted to fluidly isolate the first air filter from the liquid in the thermal control unit if the level of the liquid in the thermal control unit exceeds a threshold. 
     
     
       3. The thermal control unit of  claim 2 , wherein the plug floats in the liquid. 
     
     
       4. The thermal control unit of  claim 3 , wherein the plug rises and falls with rising and falling levels of the liquid in the thermal control unit. 
     
     
       5. The thermal control unit of  claim 4 , wherein the plug sealingly engages an aperture when the plug rises past a threshold height, the aperture being positioned between the first air filter and the liquid. 
     
     
       6. The thermal control unit of  claim 1 , wherein the first air filter has a pore size adapted to filter out particles of 0.2 microns or larger. 
     
     
       7. The thermal control unit of  claim 1 , wherein the second air filter has a pore size adapted to filter out particles of 0.2 microns or larger. 
     
     
       8. The thermal control unit of  claim 1 , further including a check valve positioned between the reservoir and the fluid circuit, the check valve adapted to prevent the liquid from flowing out of the fluid circuit and into the reservoir. 
     
     
       9. The thermal control unit of  claim 1 , wherein the liquid filter is integrated into a removable lid adapted to be selectively attached to, and detached from, the reservoir. 
     
     
       10. The thermal control unit of  claim 9 , wherein the reservoir is adapted to be lifted out of the thermal control unit without leaking the liquid. 
     
     
       11. A thermal control unit comprising:
 a fluid circuit having a fluid outlet adapted to couple to a fluid supply line and a fluid inlet adapted to couple to a fluid return line; 
 a reservoir for supplying a liquid to the fluid circuit; 
 a heat exchanger in the fluid circuit and adapted to change a temperature of the liquid in the fluid circuit; 
 a pump for circulating the liquid supplied by the reservoir through the fluid circuit; 
 a combined air and liquid filter coupled to the reservoir, the combined air and liquid filter adapted to filter liquid poured into the reservoir and to filter air escaping from the reservoir; 
 an air eliminator for venting air from the fluid circuit to the ambient surroundings, the air eliminator including an air filter and a plug having a position that varies in response to a level of the liquid in the thermal control unit, the air filter adapted to filter particulates from air passing through the air filter, and the plug adapted to fluidly isolate the air filter from the liquid in the thermal control unit if the level of the liquid in the thermal control unit exceeds a threshold; and 
 a controller adapted to control the heat exchanger such that a temperature of the circulating liquid is adjustable toward a desired temperature. 
 
     
     
       12. The thermal control unit of  claim 11 , wherein the plug rises and falls with rising and falling levels of the liquid in the thermal control unit, and the plug sealingly engages an aperture when the plug rises past a threshold height, the aperture being positioned between the air filter and the liquid. 
     
     
       13. The thermal control unit of  claim 12 , further including a check valve positioned between the reservoir and the fluid circuit, the check valve adapted to prevent the liquid from flowing out of the fluid circuit and into the reservoir. 
     
     
       14. The thermal control unit of  claim 11 , wherein the combined air and liquid filter is integrated into a removable lid adapted to be selectively attached to, and detached from, the reservoir.